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71.
Julien Roeser Rainer Bischoff Andries P. Bruins Hjalmar P. Permentier 《Analytical and bioanalytical chemistry》2010,397(8):3441-3455
Oxidation of proteins and peptides is a common phenomenon, and can be employed as a labeling technique for mass-spectrometry-based
proteomics. Nonspecific oxidative labeling methods can modify almost any amino acid residue in a protein or only surface-exposed
regions. Specific agents may label reactive functional groups in amino acids, primarily cysteine, methionine, tyrosine, and
tryptophan. Nonspecific radical intermediates (reactive oxygen, nitrogen, or halogen species) can be produced by chemical,
photochemical, electrochemical, or enzymatic methods. More targeted oxidation can be achieved by chemical reagents but also
by direct electrochemical oxidation, which opens the way to instrumental labeling methods. Oxidative labeling of amino acids
in the context of liquid chromatography(LC)–mass spectrometry (MS) based proteomics allows for differential LC separation,
improved MS ionization, and label-specific fragmentation and detection. Oxidation of proteins can create new reactive groups
which are useful for secondary, more conventional derivatization reactions with, e.g., fluorescent labels. This review summarizes
reactions of oxidizing agents with peptides and proteins, the corresponding methodologies and instrumentation, and the major,
innovative applications of oxidative protein labeling described in selected literature from the last decade. 相似文献
72.
Danuta Dutczak Alexander Milbrat Arturas Katelnikovas Andries Meijerink Cees Ronda Thomas Jüstel 《Journal of luminescence》2012,132(9):2398-2403
This paper reports the photoluminescence and afterglow of Sr2SiO4 doped with Eu2+ and Dy3+. Factors governing the formation of the monoclinic or orthorhombic phase of this ortho-silicate are described and the impact of the crystallographic modification on the luminescence and afterglow under UV and VUV excitation are discussed and insight in factors limiting the efficiency of this yellow afterglow material is given. 相似文献
73.
Justine M. L. Corbel Dr. Joost N. J. van Lingen Dr. John F. Zevenbergen Dr. Onno L. J. Gijzeman Prof. Dr. Andries Meijerink 《Angewandte Chemie (International ed. in English)》2013,52(1):290-303
Strobes are pyrotechnic compositions which show an oscillatory combustion; a dark phase and a flash phase alternate periodically. The strobe effect has applications in various fields, most notably in the fireworks industry and in the military area. All strobe compositions mentioned in the literature were discovered by trial and error methods and the mechanisms involved remain unclear. Many oscillatory systems such as Belousov–Zhabotinsky reactions, cool flames, self‐propagating high‐temperature synthesis have been observed and theories developed to elucidate their unstable behavior based on chemical interactions or based on physical processes. These systems are compared to experimental observations made on strobe mixtures. 相似文献
74.
75.
76.
77.
Volker Bachmann Thomas Jüstel Andries Meijerink Peter J. Schmidt 《Journal of luminescence》2006,121(2):441-449
The optical properties of SrSi2O2N2 doped with divalent Eu2+ and Yb2+ are investigated. The Eu2+ doped material shows efficient green emission peaking at around 540 nm that is consistent with 4f7→4f65d transitions of Eu2+. Due to the high quantum yield (90%) and high quenching temperature (>500 K) of luminescence, SrSi2O2N2:Eu2+ is a promising material for application in phosphor conversion LEDs. The Yb2+ luminescence is markedly different from Eu2+ and is characterized by a larger Stokes shift and a lower quenching temperature. The anomalous luminescence properties are ascribed to impurity trapped exciton emission. Based on temperature and time dependent luminescence measurements, a schematic energy level diagram is derived for both Eu2+ and Yb2+ relative to the valence and conduction bands of the oxonitridosilicate host material. 相似文献
78.
We prove an Erd?s-Ko-Rado-type theorem for the Kneser graph on the point-hyperplane flag in a finite projective space. 相似文献
79.
The structural and electronic transport properties of La1−x
Ce
x
MnO3 (x=0.0–1.0) have been studied. All the samples exhibit orthorhombic crystal symmetry and the unit cell volume decreases with
Ce doping. They also make a metal-insulator transition (MIT) and transition temperature increases with increase in Ce concentration
up to 50% doping. The system La0.5Ce0.5MnO3 also exhibits MIT instead of charge-ordered state as observed in the hole doped systems of the same composition. 相似文献
80.
Kauppila TJ Kotiaho T Kostiainen R Bruins AP 《Journal of the American Society for Mass Spectrometry》2004,15(2):203-211
The ionization mechanism in the novel atmospheric pressure photoionization mass spectrometry (APPI-MS) in negative ion mode was studied thoroughly by the analysis of seven compounds in 17 solvent systems. The compounds possessed either gas-phase acidity or positive electron affinity, whereas the solvent systems had different polarities and gas-phase acidities and some of them positive electron affinities. The analytes that possessed gas-phase acidity formed deprotonated ions in proton transfer; in addition, fragments and solvent adducts were observed. The compounds of positive electron affinity formed negative molecular ions by electron capture or charge exchange and substitution products of form [M - X + O](-) by substitution reactions. The efficiency of deprotonation was decreased if the solvent used possessed higher gas-phase acidity than the analyte. Solvents of positive electron affinity captured thermal electrons and deteriorated the ionization of all the analytes. Also, the proportion of substitution products was affected by the solvent. Finally, the performances of negative ion APPI and negative ion APCI were compared. The sensitivity for the studied compounds was better in APPI, but the formation of substitution products was lower in APCI. 相似文献